$\dfrac{4}{5} - \dfrac{9}{12} = {?}$
Explanation: $ = {\dfrac{4 \times 12}{5 \times 12}} - {\dfrac{9 \times 5}{12 \times 5}} $ $ = {\dfrac{48}{60}} - {\dfrac{45}{60}} $ $ = \dfrac{{48} - {45}}{60} $ $ = \dfrac{3}{60}$